Known Book of Mormon Locations
The Simple Truth about Cumorah
1. When he first appeared to Joseph Smith, Moroni told him that the record of the Nephites had been "written and deposited" not far from his home. This means Mormon and Moroni both lived in western New York when they abridged the Nephite and Jaredite records.
2. Mormon explained that "having been commanded of the Lord that I should not suffer the records which had been handed down by our fathers, which were sacred, to fall into the hands of the Lamanites, (for the Lamanites would destroy them) therefore I made this record out of the plates of Nephi, and hid up in the hill Cumorah all the records which had been entrusted to me by the hand of the Lord, save it were these few plates which I gave unto my son Moroni." (Mormon 6:6)
3. On multiple occasions, Joseph Smith and Oliver Cowdery visited Mormon's depository of records in the Hill Cumorah in New York. For that reason, and in response to anti-Mormon claims that Joseph wrote the Book of Mormon himself, they explained it was a fact that the final battles of the Jaredites and Nephites took place in the mile-wide valley west of Cumorah. (Letter VII)
4. All of Joseph's contemporaries and Priesthood successors who have discussed Cumorah have affirmed this straightforward teaching, including members of the First Presidency speaking in General Conference.
5. Knowing that Cumorah is in New York doesn't tell us everything about Book of Mormon geography, but it tells us what we need to know to be grounded in reality. Any proposed geography that doesn't put Cumorah in New York cannot be correct.